The cradle has been in use since ancient times. Parents have found that a slow periodic movement has a pacifying effect on the child as a whole. The periodicity of these movements has normally been within the range of up to 50 cycles per minute. It has not been possible to achieve higher frequencies with cradles or hanging baskets.
For a general feeling of well-being, complete beds have been developed which have been made to vibrate through some form of imbalance. At motels, particularly in the USA, there are various devices with coin meters but these devices also have a relatively low frequency. It has been observed that discomforting vibrations have been transmitted through the buildings.
Empirically it has been found that vibrations have a tension-releasing effect on the human body. Vibration massage has long been a method applied. The vibrations are attenuated by the body being treated, and are not transmitted to the surrondings. The same is found with the sexual vibrators which have found a considerable market of late. Even here the empirical result from ancient time has now appeared in a modern form.
Modern research, particularly on infants, indicates that the crying which can be observed during the years of infancy is caused by cramp in the intestines. Cramp leads to pain which in turn leads to the very typical crying of a child which may often have the character of an environmental inconvenience--albeit temporary.
The present invention is therefore directed to diverting the cause of irritating noise from small children. Knowledge about cramp provides the solution where children should be subjected to types of vibrations which relieve the attacks of cramp. It has been found particularly suitable in this context that the frequency used for treatment should be in the region of 800-2000 vibrations per minute. The purely technical problem is subjecting the child's intestines to a pulsating mechanical load while at the same time preventing this pulsating movement from being transmitted to the surroundings as an environmental inconvenience of a type other than a child's crying.